This change extends fixes made in the last two minor
releases for related failure scenarios. The previous fixes
were narrowly tailored for the original problem reports,
but we have now recognized that any error thrown by an
encoding conversion function could potentially lead to
infinite recursion while trying to report the error. The
solution therefore is to disable translation and encoding
conversion and report the plain-ASCII form of any error
message, if we find we have gotten into a recursive error
reporting situation. (CVE-2009-0922)

Disallow CREATE CONVERSION with
the wrong encodings for the specified conversion function
(Heikki)

This prevents one possible scenario for encoding
conversion failure. The previous change is a backstop to
guard against other kinds of failures in the same area.

Fix core dump when to_char() is given format codes that are
inappropriate for the type of the data argument (Tom)

Add MUST (Mauritius Island
Summer Time) to the default list of known timezone
abbreviations (Xavier Bugaud)